diff --git a/packages/app/src/components/titlebar.tsx b/packages/app/src/components/titlebar.tsx
index e41b5dda71ed..c62f1e8cb8e3 100644
--- a/packages/app/src/components/titlebar.tsx
+++ b/packages/app/src/components/titlebar.tsx
@@ -19,6 +19,7 @@ import { applyPath, backPath, forwardPath } from "./titlebar-history"
 import { useServerSync } from "@/context/server-sync"
 import { decodeDirectory } from "@/pages/directory-layout"
 import { iife } from "@opencode-ai/core/util/iife"
+import { computeStatusLight, type StatusLightColor } from "@opencode-ai/core/session/status-light"
 import { base64Encode } from "@opencode-ai/core/util/encode"
 import { ProjectAvatar } from "@opencode-ai/ui/v2/project-avatar-v2"
 import { displayName, getProjectAvatarSource, projectForSession } from "@/pages/layout/helpers"
@@ -451,7 +452,21 @@ export function Titlebar(props: { update?: TitlebarUpdate }) {
                 (tab) => {
                   const sync = serverSync.createDirSyncContext(tab.dir)
                   const session = sync.session.get(tab.sessionId)
-                  return session ? { ...tab, info: session } : null
+                  if (!session) return null
+                  const statusColor = createMemo((): StatusLightColor | null => {
+                    const messages = sync.data.message[tab.sessionId]
+                    const lastAssistant = messages?.findLast((m) => m.role === "assistant")
+                    return computeStatusLight({
+                      enabled: !!sync.data.config.status_light,
+                      sessionStatus: sync.data.session_status[tab.sessionId],
+                      messages,
+                      pendingInput:
+                        (sync.data.permission?.[tab.sessionId]?.length ?? 0) > 0
+                        || (sync.data.question?.[tab.sessionId]?.length ?? 0) > 0,
+                      parts: lastAssistant ? sync.data.part[lastAssistant.id] : undefined,
+                    })
+                  })
+                  return { ...tab, info: session, statusColor }
                 },
               )
 
@@ -494,6 +509,7 @@ export function Titlebar(props: { update?: TitlebarUpdate }) {
                             project={projectForSession(tab.info, projects(), projectByID())}
                             directory={tab.dir}
                             sessionId={tab.info.id}
+                            statusColor={tab.statusColor}
                             onClose={() => tabsStoreActions.removeTab(tab.href)}
                           />
                         </>
@@ -736,6 +752,7 @@ function TabNavItem(props: {
   directory: string
   sessionId: string
   hideClose?: boolean
+  statusColor: () => StatusLightColor | null
   onClose: () => void
 }) {
   const match = useMatch(() => props.href)
@@ -761,6 +778,16 @@ function TabNavItem(props: {
         <span data-slot="project-avatar-slot">
           <ProjectTabAvatar project={props.project} directory={props.directory} sessionId={props.sessionId} />
         </span>
+        {props.statusColor() && (
+          <div
+            class="size-1.5 shrink-0 rounded-full"
+            classList={{
+              "bg-icon-success-base": props.statusColor() === "green",
+              "bg-surface-warning-strong": props.statusColor() === "yellow",
+              "bg-text-diff-delete-base": props.statusColor() === "red",
+            }}
+          />
+        )}
         <span class="min-w-0 flex-1">{props.title}</span>
       </a>
 
diff --git a/packages/core/src/session/status-light.ts b/packages/core/src/session/status-light.ts
new file mode 100644
index 000000000000..6e61ac23c6b2
--- /dev/null
+++ b/packages/core/src/session/status-light.ts
@@ -0,0 +1,27 @@
+export type StatusLightColor = "green" | "yellow" | "red"
+
+export function computeStatusLight(input: {
+  enabled: boolean
+  sessionStatus?: { type: string }
+  messages?: readonly { role: string; id: string }[]
+  pendingInput: boolean
+  parts?: readonly { type: string; state?: { status?: string }; synthetic?: boolean; ignored?: boolean }[]
+}): StatusLightColor | null {
+  if (!input.enabled) return null
+  if (!input.sessionStatus || input.sessionStatus.type === "idle") return "green"
+  if (!input.messages) return "green"
+  if (input.pendingInput) return "green"
+  const lastAssistant = input.messages.findLast((m) => m.role === "assistant")
+  if (!lastAssistant) return "yellow"
+  if (!input.parts) return "yellow"
+  if (
+    input.parts.some(
+      (p) => p.type === "tool" && (p.state?.status === "running" || p.state?.status === "pending"),
+    )
+  )
+    return "red"
+  if (input.parts.some((p) => p.type === "text" && !p.synthetic && !p.ignored)) return "red"
+  return "yellow"
+}
+
+export * as StatusLight from "./status-light"
diff --git a/packages/opencode/src/cli/cmd/tui/app.tsx b/packages/opencode/src/cli/cmd/tui/app.tsx
index c889817be2a7..b588e99fc13e 100644
--- a/packages/opencode/src/cli/cmd/tui/app.tsx
+++ b/packages/opencode/src/cli/cmd/tui/app.tsx
@@ -20,6 +20,7 @@ import {
 } from "solid-js"
 import { win32DisableProcessedInput, win32FlushInputBuffer, win32InstallCtrlCGuard } from "./win32"
 import { Flag } from "@opencode-ai/core/flag/flag"
+import { computeStatusLight } from "@opencode-ai/core/session/status-light"
 import semver from "semver"
 import { DialogProvider, useDialog } from "@tui/ui/dialog"
 import { DialogProvider as DialogProviderList } from "@tui/component/dialog-provider"
@@ -451,29 +452,50 @@ function App(props: { onSnapshot?: () => Promise<string[]> }) {
     kv.get("paste_summary_enabled", !sync.data.config.experimental?.disable_paste_summary),
   )
 
+  const STATUS_EMOJI = { green: "\u{1F7E2} ", yellow: "\u{1F7E1} ", red: "\u{1F534} " } as const
+
+  const trafficLight = createMemo(() => {
+    if (!sync.data.config.status_light) return ""
+    if (route.data.type === "home") return STATUS_EMOJI.green
+    if (route.data.type !== "session") return ""
+    const sid = route.data.sessionID
+    const messages = sync.data.message[sid]
+    const lastAssistant = messages?.findLast((m) => m.role === "assistant")
+    const color = computeStatusLight({
+      enabled: true,
+      sessionStatus: sync.data.session_status?.[sid],
+      messages,
+      pendingInput:
+        (sync.data.permission?.[sid]?.length ?? 0) > 0
+        || (sync.data.question?.[sid]?.length ?? 0) > 0,
+      parts: lastAssistant ? sync.data.part[lastAssistant.id] : undefined,
+    })
+    return color ? STATUS_EMOJI[color] : ""
+  })
+
   // Update terminal window title based on current route and session
   createEffect(() => {
     if (!terminalTitleEnabled() || Flag.OPENCODE_DISABLE_TERMINAL_TITLE) return
 
     if (route.data.type === "home") {
-      renderer.setTerminalTitle("OpenCode")
+      renderer.setTerminalTitle(trafficLight() + "OpenCode")
       return
     }
 
     if (route.data.type === "session") {
       const session = sync.session.get(route.data.sessionID)
       if (!session || SessionApi.isDefaultTitle(session.title)) {
-        renderer.setTerminalTitle("OpenCode")
+        renderer.setTerminalTitle(trafficLight() + "OpenCode")
         return
       }
 
       const title = session.title.length > 40 ? session.title.slice(0, 37) + "..." : session.title
-      renderer.setTerminalTitle(`OC | ${title}`)
+      renderer.setTerminalTitle(trafficLight() + `OC | ${title}`)
       return
     }
 
     if (route.data.type === "plugin") {
-      renderer.setTerminalTitle(`OC | ${route.data.id}`)
+      renderer.setTerminalTitle(trafficLight() + `OC | ${route.data.id}`)
     }
   })
 
diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index 8dc8c6ee54a8..701ff64c88d1 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -307,6 +307,9 @@ export const Info = Schema.Struct({
       }),
     }),
   ),
+  status_light: Schema.optional(Schema.Boolean).annotate({
+    description: "Show traffic light status indicator in terminal title",
+  }),
 }).annotate({ identifier: "Config" })
 
 // Uses the shared `DeepMutable` from `@opencode-ai/core/schema`. See the definition
diff --git a/packages/sdk/js/src/v2/gen/types.gen.ts b/packages/sdk/js/src/v2/gen/types.gen.ts
index d70c7a887576..2b32aa2edb23 100644
--- a/packages/sdk/js/src/v2/gen/types.gen.ts
+++ b/packages/sdk/js/src/v2/gen/types.gen.ts
@@ -1910,6 +1910,7 @@ export type Config = {
     mcp_timeout?: number
     policies?: Array<ConfigV2ExperimentalPolicy>
   }
+  status_light?: boolean
 }
 
 export type Model = {